This invention relates to an image forming apparatus such as a digital color copying apparatus for copying a color picture and also to an image processing apparatus for processing a color image picked up from a picture by such an image forming apparatus.
Generally, the operation of copying an original by means of a copying machine falls in one of the three categories listed below.
(1) The original is in black and white and the copy is required to be also in black and white.
(2) The original is in color and the copy is required to be in black and white.
(3) The original is in color and the copy is required to be also in color.
With known color copying apparatus, the user trying to carry out an operation of copying the original in any of the above three categories either
(1) copies the original in color regardless of the type of the original or
(2) selects a color copying mode or a in black and white copying mode depending on the type of the original.
If the original comes in the form of a single sheet or a few number of sheets, the user may select a color mode or a monochrome mode for each sheet without any trouble. When the original has a large number of sheets and an automatic draft feeder (ADF) is employed for feeding them, either a color mode or a monochrome mode will be selected for copying if the original contains both color and monochromatic pictures. Thus, it is difficult to select properly a color mode or a monochrome mode for each sheet if the original contains both color and monochromatic pictures.
A color copying machine that can automatically select a color mode has recently been proposed. A color copying machine of this type is provided with a pre-scanning feature of analyzing the chromatic distribution of each sheet of the original to determine if the picture of sheet is in black and white or in color and selecting either a color mode or a monochrome mode for copying the sheet depending on the outcome of the analysis.
Thus, with a color copying machine having such a feature, it is not difficult to select properly a color mode or monochrome mode for each sheet of the original when the original has a large number of sheets and contains both color and monochromatic pictures and an ADF is employed for copying.
As described above, a color copying machine having an automatic color/monochrome mode selection feature pre-scans each of the sheets of the original before actually copying it in order to analyze its chromatic distribution and determine if it is in black and white or in color before it selects a color mode or a monochrome mode for copying it. Thus, such a machine can cope with an original comprising a large number of sheets that are fed by an ADF if the original contains both color monochromatic pictures.
However, the feature of automatically selecting a color mode or a monochrome mode is adapted to discriminate between a picture in color and a picture in black and white and the result of the discrimination may not necessarily agree with the intention of the user who may want to obtain a monochromatic copy of a color picture.
For example, a faintly colored sheet carrying thereon characters written with black ink (with a black pencil) that provides a color original will also be determined to be so by a color copying machine having an automatic mode selection feature, whereas the user will more often than not want a monochromatic copy out of it.
Handbills and leaflets are often prepared by printing letters with black ink on colored sheets of paper in order to obtain an esthetic effect at reduced cost. When such a printed sheet of paper is copied, it will be done so mostly to copy the message on the sheet and the color of the sheet will not have any significance to the person who wants the copy.
In short, whether the user selects a color mode or a monochrome mode is not simply dependent on if the original is in color or in black and white.
While the prior art is discussed above from the viewpoint of the operation by the user of an image forming apparatus who is copying the original, it will also have to be discussed from the viewpoint of the rate of ink consumption.
If a page of a faintly colored note book carrying thereon characters written with black ink (with a black pencil) is copied in color, a large volume of coloring matter will have to be consumed for copying the colored background that occupies most of the surface area relative to the area occupied by the black characters on the page.
Likewise, a large volume of coloring matter will have to be consumed for copying the background of a handbill or a leaflet that is colored. The consumption of the costly coloring matter will be avoided if they are copied in black and white.
Therefore, there is a demand for a color copying apparatus having an automatic color/monochrome mode section feature that is adapted to occasions as described above.
Therefore, it is an object of the present invention to provide an image forming apparatus that can copy an original by automatically selecting a color mode or a monochrome mode for each sheet of the original if the latter contain pictures in color and those in black and white as well as an image processing apparatus for processing an image picked up by such an image forming apparatus.
Another object of the invention is to provide an image forming apparatus that can automatically select a color mode or a monochrome mode according to a set of preselected conditions for copying an original without simply depending on if the original is in color or in black and white as well as an image processing apparatus for processing an image picked up by such an image forming apparatus.
Still another object of the invention is to provide an image forming apparatus that can produce a black and white copy from an original of a colored sheet carrying thereon characters printed with black ink at low cost as well as an image processing apparatus for processing an image picked up by such an image forming apparatus.
According to an aspect of the invention, the above objects and other objects are achieved by providing an image forming apparatus comprising a reading means for reading an original and outputting image data including color information for the original and an image forming means for determining an image to be formed either in black and white or in color according to the color information of the image data and forming an image from the image data according to the determination (Embodiments 1 through 5; FIGS. 4, 14, 16, 20, 22).
With the above described arrangement, an image forming apparatus according to the invention does not simply produce a black and white copy out of a black and white original sheet or a color copy out of a color original sheet but optimally selects a color mode or a monochrome mode for the original sheet or each of the original sheets according to a predetermined rule so that, for example, a black and white image will be produced out of a color original sheet carrying thereon monochromatic characters printed on a colored background.
According to another aspect of the invention, there is provided an image forming apparatus comprising a reading means for reading an original and outputting image data including color information for the original, a determining means for determining a region for the image data output from the reading means and an image forming means for determining an image to be formed either in black and white or in color according to the color information of the image data and the region determined by the determining means and forming an image from the image data according to the determination (Embodiments 6 through 8; FIGS. 24, 28, 30).
With the above described arrangement, an image forming apparatus according to the invention determines a region according to the color information of the original sheet or each of the original sheets and an image to be formed either in black and white or in color according to the color information and the region so that it selects a color mode or a monochrome mode more reliably.
More specifically, for copying an original sheet by means of an image forming apparatus according to the invention, it determines if the original is to be copied in color or in black and white by pre scanning the original and analyzing its chromatic distribution and then automatically selects a color mode or a monochrome mode according to the determination before it produces a copy of the original. Thus, an image forming apparatus according to the invention can cope with an original comprising a large number of sheets that are fed by an ADF if the original contains both color monochromatic pictures.
Additionally, an image forming apparatus according to the invention is free from the above pointed out problem of a known image forming apparatus having the feature of automatically selecting a color mode or a monochrome mode that the result of the discrimination made by the apparatus between a picture in color and a picture in black and white for the original to be copied may not necessarily agree with the intention of the user who may want to obtain a monochromatic copy of a color picture.
For example, a faintly colored sheet carrying thereon characters written with black ink (with a black pencil) may be copied in black and white, if the user wants so, by preselecting an appropriate set of conditions.
Handbills and leaflets prepared by printing letters with black ink on colored sheets of paper may also be copied in black and white.
In other words, an image forming apparatus according to the invention automatically selects a color mode or a monochrome mode according to a set of conditions preselected by the user regardless if the original sheet to be copied is in color or in black and white.
Thus, with an image forming apparatus according to the invention, faintly colored sheets carrying thereon characters written with black ink (with a black pencil) and handbills and leaflets prepared by printing letters with black ink on colored sheets of paper may be copied in black and white to suppress the consumption of costly coloring matters and hence the total cost of producing copies.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinbefore.